Valveless rock-drill.



No. 68I,428. Patented Aug. 27, MIDI.

R. L. AMBROSE.

VALVELESS ROCK DRILL.

(Application filed Nov. 15, 1900. (No Model.) 2 sheets-shut, l.

WITNESSES: INVENTOR W I I WJMQ m: nonm: raga: co. movauvua. WASflINGTON a. c

Patented Aug 27, 190:.

,B. L. AMBROSE. VALVELESS ROCK DRILL.

(Application filed Nov. 16, 1900.)

2 Sheets-Sheet 2,

(No ModelJ I INVENTOR Maia HIS ATTURNEY WITNESSES n1: 0am; PUEM 00v. morauma. wAsmumou. B. C.

UNITED STATES PATENT OFF C ROBERT L. AMBROSE, OF TARRYTOWVN, NEW YORK, ASSIGNOR TO RAND DRILL COMPANY, OF NEW YORK, N. Y.

'VALVELESS ROCK-DRILL.

SPECIFICATION forming part of Letters Patent No. 681,428, dated August 27,1901.

Application filed November 15, 1900. serial No. 36,633- (llomodelJ To-aZZ whom it may-concern.-

Be it known that 1, ROBERT L. AMBROSE, a citizen of the United States of America, residing at Tarrytown, in the county of l/Vestchesfor and State of New York, have invented certain new and useful Improvements in Valvesaid ports, the said ports having certain defia nite relations with respect to each other and to the piston, as shallhereinafter be more fully set forth; and the objects of my invention are to improve and simplify the construction of rock-drills and to so locate the aforesaid ports with respect to each other and to the piston as to give the greatest efiiciency and economy of motive fluid in operation. I will now proceed to describe a valveless rock-drill embodying my invention and will then point out the novel features in claims.

In the drawings, Figure 1 is a central longitudinal section of a valveless rock-drill em- 0 bodying my invention. Figs. 2, 3, 4, and 5 are diagrammatic views illustrating certain portions of my improved rock-drill and showing the relationship of certain parts in their various positions.

The rock-drill comprises a cylinder, (designated by the reference character a.) A piston b is mounted to reciprocate within the cylinder, and the said piston may be provided with the usual piston-rod c, to which may be se- 0 cured the ordinary form of drill chuck or head, as may be desired. Lower and upper heads d and e are provided, which may be of the usual or any desired form, and suitable rotating mechanismf may be carried in the 5 upper cylinder-head, as is usual in this type of drill. The cylinder may be mounted upon the usual shell g, and feeding mechanism may be provided.

Further detail description of the parts 0, d, 0 e,f, and g is unnecessary, as these parts form no portion of my present invention, all of which lies in the combination of the piston of the cylinder is designated by the reference character '6. The exhaust-port for the forward end of the cylinder is designated by the reference character j and for the rear end of the cylinder by the reference character 70. I have shown the exhaust-ports j and k as openingin the side of the cylinder and communi eating directly with the atmosphere for purposes of clearness of illustration. In practice these ports may open into a chamber, or pipe connections may be made thereto, all in a manner well known.

The common inlet-port is designated by the reference character Z, and the said inlet-port is arranged to communicate with an annular channel m around the interior of the cylinder.

The piston 17 has a reduced central portion n, which terminates in a shoulder 0 toward the forward end of the piston and a shoulder go toward the rear end of the piston. The admission and exhaust ports are controlled by the forward and rear ends of the piston and by the shoulders 0 9 thereof in its movement. With the piston in the position in which it is shown in Figs. 1 and 5 the admission-port t' to the rear end of the cylinder is open to the inlet-port Z through the inlet-chamber m, while the admission-port h at the forward end of the cylinder is closed to the inlet-port Zby the fact that the forward end of the piston overlies that portion of the'cylinderwhich is between the said admission-port h and the inlet-chamber m. The exhaust-portj at the forward end of the cylinder is open to atmosphere, while the exhaust-port it at the rear end of the cylinder is closed by the rear portion of the piston b,which overlies same. The piston b is shown at the extreme end of a stroke in the rearward direction, and in such posi tion it will be seen that although the admission-port t is open to the inlet-port Z the rear cylinder) has been overridden by the piston, and is hence closed thereby. The piston in the last part of its movement, howeverthat is to say, in that portion of its movement after it has overridden the end of the said port-will compress the motive fluid, which is now locked in the end of the cylinder against escape, and the same will act as a cushion to such final movement. Further, by its expansive force it will start the piston on its return movement until the rear end of the said port 1' shall be uncovered by the piston. Motive fluid then passing through the inlet-port 1, channel m, and admission-port l will enter the rear end of the cylinder and will continue to force the piston forward until the shoulder 12 thereon overrides the forward end of the admission-port 2'. Motive fluid will then be cut off. During all the movement of the piston up to this point the exhaust-portj at the forward end of the cylinder will have been open, and the forward end of the cylinder will thus have been open free to exhaust. At the moment that the shoulder 19 cuts off admission to the rear end of the cylinder by overriding the forward end of the port 'i the forward end of the piston 12 will have overridden the eXhaust-portj at the forward end of the cylinder, and further move ment of the piston will be due to the expansion of the motive fluid which is locked in the rear end of the cylinder, such movement of the piston continuing under the influence of such expansion until the rear end of the piston reaches such a point as to open the exhaust-port 26 at the rear end of the cylinder to atmosphere. I have found that such distance of travel should be equal to about one-fifth of the entire stroke of the piston, and I have also found that most eflicient and economical results have been obtained by providing also that this expansion period should take place while and, only while both ends of the cylinder are closed to both admission and exhaust. An examination of the diagrams of Figs. 3 and 4 will clearly illustrate that the arrangements of ports herein shown effects this result. At the moment the piston arrives at such a point as to open the rear end: of the cylinder to exhaust through the exhaust-port 7c the shoulder 0. of the said piston will have reacheda point where itwill place in communication the admission-port h at the forward end of the cylinder with the inlet-port Z through the reduced central portion of the piston and the inlet-channelm. (SeeFig. 3.) Furthermovement of the piston will be due toits own momentum,and allof the further movement will be against the full pressure of the motive fluid. The proportions of the parts and the location of the ports with respect to each other and to the piston are such that the piston will continue to advance, owing to the great momentum that it has acquired until it is itself.

stopped by the drill-rod, which it carries, coming in contactwith a portion of rock upon which it is being operated, or until the piston itself is otherwise stopped mechanically. When the piston b has lost its acquired momentum, the motive fluid which is admitted at the forward end of the cylinder through the admission-port h will operate to force the piston rearwardly. It will be noted, however, that the point of admission cut-off with respect to a full stroke of the piston is very much earlier in the rearward movement of the piston than in the forward movement. In practice I have found that the correct proportion is about as one is to two. Then the motive fluid has been cut off by the shoulder 0 overriding the rear end of the admission-port 72,,the following portion of the rearward stroke of the piston will be due to the expansive quality of the motive fluid which is locked in the forward end of the cylinder. At the moment the admission cut-off at the forward end of the cylinder was effected by the piston the exhaust at the rear end of the cylinder was also effected, and thus, as in the forward stroke, this expansion period of the rearward stroke is effected while both ends of the cylinder are closed to both admission and exhaust. The last portion of the rearward movementwill, as in the forward movement, be due to momentum, but in the rearward movement it is not desired to strike a blow, and hence provision must be made for absorbing the momentum within the rock-drill It is of course very undesirable that the piston should strike against the rear head of the cylinder, for the reason that if such were permitted it would be very likely to burst the bolts which hold the rear cylinderhead in position, and failing that would be likely to damage the rotating mechanism which is generally carried in the rear head. I have hence arranged the admission cut-off very much earlier in a stroke in the rearward direction than in a stroke in the forward direction, and I have provided that the last portion of the movement of a stroke in the rearward direction shall be against motive fluid which is locked against exhaust in the rear end of the cylinder and which thus forms a powerful cushion. In the proportions shown herein the cushion is sufficient to prevent the piston from striking the rear head while at the same time it is not sufficient to prevent a substantially full stroke of the piston. This latter is important, for the reason that if the movement of the piston is reversed before it has reached the end of its stroke the downward stroke of the piston will lose much of its effective force.

I am aware that valveless rock-drills have been experimented with for many years and that a number of patents have been granted upon them; but these rock-drills have all been defective because of the incorrect relationship of the ports with respect to each other and to the piston. I have found that a certain definite relationship of the ports with respect to each other and to the piston is absolutely necessary for efiicient and economical results, and such relationship of ports I have herein shown, described, and pointed out in claims.

In the drill which I have successfully operated and from which the drawings forming a part of this specification have been made I have proportionated the parts and arranged the ports about as follows.

I have arranged that a full stroke of the piston shall consist of a travel of five and three-quarter inches, that upon a rearward stroke admission cut-off shall take place after a movement of one and five-eighths inches, that during all of this movement the rear end of the cylinder shall be open and free to exhaust, that the following movement of one and one-eighth inches shall be a period of expansion and that the said period of expansion shall take place with the cylinder closed at both ends to both admission and exhaust, and that the remaining three inches of movement shall be against the pressure of motive fluid at the rear end and with the forward end of the cylinder open to exhaust. With these proportions it will be seen that admission cut-off and release at the forward end are respectively simultaneous with exhaust closure and admission at the rear end, but are very much earlier in a rearward stroke than in a forward stroke. It will also be seen that the expansion of the working fluid at either end is while and only while the other end is closed to both admission and exhaust, and further that this expansion period takes place very much earlier in the rearward stroke than in the forward stroke.

It is very essential that in the early portion of the rearward stroke of the piston there shall be a high lifting power, for the reason that in rock-drilling the drill often becomes more or less jammed in the hole and requires considerable force to start it out. Once started the power required to continue the movement is very much less, and, as before explained, in the latter part of the rearward stroke the movement of the piston needs to be heavily cushioned. In my arrangement of parts andlocation of ports I have provided great lifting power for the piston in the first portion of the return or rearward stroke thereof. I have then quickly cut off the ad mission of the motive fluid and have used the same expansively for the next portion of the stroke, and have thus obtained an effective power, coupled with economy of working. Lastly, I have provided a cushion at the rear end of such quality as to correctly balance the force of momentum acquired.

In operation the expansion of the motive fluid takes place while and only while both ends of the cylinder are closed to both admission and exhaust. I have in this arrangement not only obtained a high efficiency in work, but a great economy of motive fiuid. While so working expansively at one end of the cylinder by closing the other end to both admission and exhaust I obtain a small initial pressure of the motive fluid, which is locked in the other end. Such amount is not sufiicient to seriously check the piston in its movement, the slight tendency to check the same being rather beneficial thanv otherwise. When the admission is opened in the continuance of the movement of the piston at that end of the cylinder in advance of the piston in its movement and at which the said initial proportion has taken place, the motive fluid will enter against partially-compressed air, and will hence not only fill the cylinder-space quicker, but a smaller quantity of motive fluid will be required to so fill it than if the motive fluid were to enter against free and uncompressed air.

In a series of tests which I have made I have found a very high degree of economy coupled with a very great efficiency has resulted from the arrangement and proportion herein described, shown, and claimed.

What I claim is- 1. In a valveless rock-drill, the combination with a cylinderhaving separate admission and exhaust ports for each end of the cylinder and a common inlet-port, of a piston, having a reduced central portion and adapted to control the said ports, the said ports being so located 'with respect to each other and to the piston that during a rearward stroke of the piston, admission cut-off at the forward end is substantially simultaneous with exhaust-closure at the rear end but is earlier with respect to a full stroke of the piston than the corresponding point of admission cut-01f at the rear end during a forward stroke.

2. In a valveless rock-drill, the combination with a cylinder having separate admission and exhaust ports for each end of the cylinder,and a common inlet-port, of a piston, having a reduced central portion and adapted to control the said ports, the said ports being so located with respect toeach other and to the piston, that during a rearward stroke of the piston, release at the forward end is substantially si multaneous with admission at the rear end but is earlier with respect to a full stroke of the piston than the corresponding point of release at the rear end during a forward stroke.

3. In a valveless rock-drill, the combination with a cylinder having separate admission and exhaust ports for each end of the cylinder,and a common inlet-port, of a piston, having areduced central portion and adapted to control the said ports, the said ports being so located with respect to each other and to the piston that during a rearward stroke of the piston, admission cut-off and release at the forward end are respectively substantially simultaneous with exhaust-closure and admission at the rear end but are respectively earlier with respect to a full stroke of the piston than the corresponding points of admission cut-oft and release at the rear end during a forward stroke.

4. In a valveless rock-drill, the combination with a cylinder havingseparate admission and exhaust ports for each end of the cylinder, and a common inlet-port, of a piston, having a reduced central portion and adapted to control the said ports, the said ports being so located with respect to each other and to the piston that during a rearward stroke of the piston, exhaust-closure at rear end is substantially simultaneous with admission cut-ofi at the forward end but is prior to exhaust-release thereat.

5. In a valveless rock-drill, the combination with a cylinder having separate admission and exhaust ports for each end of the cylinder, and a common inlet-port, of a piston, having a reduced central portion and adapted to control the said ports, the said ports being so located with respect to each other and to the piston, that during a rearward stroke of the piston, release at the forward end is substantially simultaneous with admission at the rear end but is subsequent to exhaust-closure thereat.

6. In a valveless rock-drill, the combination with a cylinder havingseparate'admission and exhaust ports for each end of the cylinder, and a common inlet-port, of a piston, havinga reduced central portion and adapted to control the said ports, the said ports being so located with respect to each other and to the piston, that during a rearward stroke of the piston, exhaust closure and admission at the rear end are respectively substantially simultaneous with admission cut-off and release at the forward end but that exhaust-closure, forward of the piston in its movement in either direction, takes place prior to exhaust-release rearward thereof.

7. In a valveless rock-drill, the combination with a cylinder, having separate admission and exhaust ports for each end of the cylinder, and a common inlet-port, of a piston, having a reduced central portion and adapted to control the said ports, the said ports being so located with respect to each other and to the piston that the expansion of working fluid at the forward end of the cylinder takes place while, and only while, the rear end of the cylinderis closed to both admission and exhaust, but that the expansion period is later, with respect to a full stroke of the piston, during a forward stroke than during a rearward stroke.

8. In a valveless rock-drill, the combination with a cylinder having separate admission and exhaust ports for each end of the cylinder, and a common inlet-port, of a piston, having a reduced central portion and adapted to control the said ports, the said ports being so located with respect to each other and to the piston, that the expansion of the working fluid at the rear end of the cylinder takes place while, and only while, the forward end of the cylinder is closed to both admission and exhaust, but that the expansion period is later, with respect to a full stroke of the piston, during a forward stroke than during a rearward stroke. 9. In avalveless rock-drill,the combination with a cylinder having separate ad mission and exhaust ports for each end of the cylinder, and a common inlet-port, of a piston, having a reduced central portion and adapted to control the said ports, the said ports being so located with respect to each other and to the piston that the expansion of working fluid at either end of the cylinder takes place while, and only while, the other end of the cylinder is closed to both admission and exhaust, but that the expansion period is later, with respect to a full stroke of the piston, during a forward stroke than during a rearward stroke.

10. In a valveless rock-drill, the combination with a cylinder having separate admission and exhaust ports for each end of the cylinder, and a common inlet-port, of a piston, having a reduced central portion and adapted to control the said ports, the said ports being so located with respect to each other and to the piston that the expansion period of a stroke in either direction is substantially equal, but is later with respect to a full stroke of the piston, during a forward stroke than during a stroke in the rearward direction.

11. In a valveless rock-drill, the combination with a cylinder having separate admission and exhaust ports for each end of the cylinder, and a common inlet-port, of a piston, having a reduced central portion and adapted to control the said ports, the said ports being so located with respect to each other and to the piston, that the distance traveled by the piston up to the point of admission cut-oft, during a full stroke in either direction, is substantially equal to the distance traveled by the piston during exhaust period in a full stroke in the other direction, but is substantially twice as great during a full stroke in the forward direction, asduring a full stroke in the rearward direction.

12. In a valveless rock-drill, the combination with a cylinder having separate admission and'exhaust ports for each end of the cylinder, and a common inlet-port, of a piston, having a reduced central portion and adapted to control the said ports,'the said ports being so located with respect to each other and to the piston, that the expansion period of a stroke in either direction is substantially equal, the distance traveled by the piston up to the point of admission cut-ofi, during a full stroke in one direction, being substantially equal to the distance traveled by the piston during exhaust period in a full stroke in the other direction, but substantially twice as great during a full stroke in the forward direction, as during a full stroke in the rearward direction.

13. In a valveless rock-drill, the combination with a cylinder having separate admission and exhaust ports for each end of the cylinder, and a common inlet-port, of a piston, having a reduced central portion and adapted to control the said ports, the said ports being period in a full stroke in the other direction, IO so located with respect to each other and to but is substantially twice as great during a the piston, that the expansion period of a full stroke in the forward direction, as during stroke in either direction is about equal to a full stroke in the rearward direction. one-fifth of a full stroke, and that the distance traveled by the piston up to the point ROBER F AMBROSE of admission cut-off, during a full stroke in Witnesses:

one direction, is substantially equal to the dis- HUGH V. CONRAD,

tance traveled by the piston during exhaust WILLIAM STEVENS BARNUM. 

